The law relating radiated energy to temperature, proved theoretically by Boltzmann, is named after:

1. The relation was first found experimentally. 2. It was later given a theoretical basis. 3. Obtained experimentally by Stefan and proved theoretically by Boltzmann, it is the Stefan-Boltzmann law. 4. The constant sigma is the Stefan-Boltzmann constant. _Source: syllabus Physics Part II, Ch 10 'Thermal Properties of Matter'_